Deepika Narasimha

Arrhythmias in Women

There are important gender differences in cardiac electrophysiology that affect the epidemiology, presentation, and prognosis of various arrhythmias. Women have been noted to have higher resting heart rates compared to men. They also have a longer QT interval, which puts them at an increased risk for drug‐induced torsades de pointes. Women with atrial fibrillation are at a higher risk of stroke, and they are less likely to receive anticoagulation and ablation procedures compared to men. Women have a lower risk of sudden cardiac death and are less likely to have known coronary artery disease at the time of an event compared to men. Both men and women have been shown to derive an equal survival benefit from implantable cardioverter defibrillators and cardiac resynchronization therapy, although these devices are significantly underutilized in women. Women also appear to have a better response to cardiac resynchronization therapy in terms of reduced numbers of hospitalizations and more robust reverse ventricular remodeling. Further studies are required to elucidate the underlying pathophysiology of these sex differences in cardiac arrhythmias.

Sex Differences in Utilisation and Response to Implantable Device Therapy

Multiple studies have demonstrated that implantable cardioverter-defibrillators (ICDs) and cardiac resynchronisation therapy (CRT) provide significant mortality and morbidity benefits to eligible patients irrespective of gender. However, female patients are less likely to receive this life-saving therapy and are significantly under-represented in cardiac device trials. Various performance improvement programmes have proved that this gender disparity can be reduced and these therapies should be offered to all eligible patients regardless of sex. Efforts should be made to enrol more women in clinical trials and sex-specific analysis in medical device clinical studies should be encouraged. In this article we review the data on sex differences in clinical outcomes with ICDs and CRT and explore the reasons for this sex-based disparity.

Economic Evaluations of Hematological Malignancies Compared with Solid Tumors

Introduction: Cancer care costs escalated with the introduction of novel therapies. Therefore, cancer–related Cost Utility Analyses (CUAs) are used to guide policy makers. Since numerous methods (criteria) exist to evaluate CUAs, we compared these criteria between CUAs of solid tumors and those of hematological malignancies. Methods: A systemic MEDLINE search of English-language publications between 2001 and 2012 was performed. Strict inclusion criteria were limited to CUAs examining one single intervention and one single study comparator. Standard data of 66 variables, based on the Drummond criteria, were collected to review each CUA for clarity, completeness, and health economic methodological quality. Results: Among 8,515 screened papers on Pubmed, 177 cancer-related CUAs (2%) were eligible. Solid tumors and hematological malignancies CUAs constituted 161(91%) and 16(9%). Among the standardized methods for evaluating CUAs, those of solid tumors reported more frequently the presentation of cost-effectiveness acceptability curve (p=0.02) and the use of threshold value to interpret study results (p=0.024) than those of hematological malignancies. Further, CUAs of solid tumors were more frequently multicenter-based (p=0.014); however, CUAs of hematological malignancies listed differential quality adjusted life year separately more frequently (p=0.02). Outcomes of CUAs of solid tumors were more frequently reported as significant (p=0.014). Conclusions: CUAs of solid tumors abided more frequently with the standardized methods (criteria) than those of hematological malignancies, which may be due in part to their multiple study sites. CUAs of hematological malignancies may warrant more methodological standardization and incorporate more study sites.

Efficacy of Intravenous Magnesium in Facilitating Cardioversion of Atrial Fibrillation

Background—Low serum magnesium (Mg) levels are associated with an increased risk of atrial fibrillation. Some studies have shown a benefit of Mg in facilitating pharmacological cardioversion. The role of an intravenous infusion of Mg alone in facilitating electric cardioversion is not clear. Methods and Results—In a prospective, randomized, double-blind, placebo-controlled trial, we enrolled patients with atrial fibrillation who were scheduled for electric cardioversion. Patients were randomized to receive Mg or placebo before cardioversion using a step-up protocol with 75, 100, 150, and 200 J biphasic shocks. Patients with hypokalemia, hypermagnesemia, or postcardiac surgery atrial fibrillation were excluded. Patients on antiarrhythmic drugs were included as long as they were at steady state. All patients were monitored for 1 hour post procedure for the maintenance of sinus rhythm. A total of 261 patients (69% male, mean age 65.5±11.1 years) were randomized (132 and 129 patients receiving Mg and placebo, respectively). Baseline characteristics were similar between both the groups. There was no statistically significant difference in the success rate of cardioversion between the 2 groups (86.4% versus 86.0%; P=0.94), cumulative amount of energy required for successful cardioversion (123.3±55.5 versus 129.5±52.6 J; P=0.40), or the number of shocks required to convert to sinus rhythm (2.25±1.24 versus 2.41±1.22, P=0.31). No adverse events were noted in either group. Conclusions—In patients undergoing electric cardioversion for persistent atrial fibrillation, Mg infusion does not increase the rate of successful cardioversion. Clinical Trial Information—URL: https://clinicaltrials.gov. Unique identifier: NCT01597557.

Arrhythmias. Cardiac resynchronization therapy in women.

A meta-analysis by investigators from FDA of three major trials of cardiac resynchronization therapy (CRT) demonstrated that women have a reduced rate of heart failure (HF) and death with CRT at a shorter QRS duration than men. Recognizing these sex-specific differences is important to improve outcomes for women with HF.

Validation of a smartphone‐based event recorder for arrhythmia detection

Ambulatory cardiac monitoring devices such as external loop recorders (ELRs) are often used in the outpatient clinic to evaluate palpitations. However, ELRs can be bulky and uncomfortable to use, especially in public, at work, or in social situations. An alternative approach is a smartphone‐based electrocardiographic (ECG) recorder/event recorder (Kardia Mobile [KM]), but the comparative diagnostic yield of each approach has not been studied.

Patent Foramen Ovale Closure for Hypoxemia

A patent foramen ovale (PFO) is a common anatomic finding in 20% of the normal population. Significant hypoxemia can occur in circumstances in which hemodynamic or anatomic changes predispose to increased right-to-left intra-atrial shunting. The subsequent hypoxemia produces substantial dyspnea that may affect the patients quality of life, independent of underlying pulmonary disease. Profound hypoxemia caused by right-to-left shunt across the interatrial septum usually responds to percutaneous PFO closure. An important impediment to successful treatment is the lack of awareness of the potential role of a PFO in this condition.